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audio(3): document audiostat/audioctl and speed+delay controls on volume

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cinap_lenrek 2011-11-02 00:17:51 +01:00
parent 096ce16818
commit 06e7cb6728
1 changed files with 39 additions and 20 deletions
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57
sys/man/3/audio
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@ -6,6 +6,8 @@ audio \- audio device
.B bind -a #A /dev
.sp 0.3v
.B /dev/audio
.B /dev/audioctl
.B /dev/audiostat
.B /dev/volume
.fi
.SH DESCRIPTION
@ -21,39 +23,56 @@ The length of the
.B audio
file as returned by
.IR stat (2)
represents the number of bytes buffered for input or output.
represents the number of bytes buffered for output.
.PP
.B Audioctl
is driver specific control file and left undocumented here.
.PP
.B Audiostat
is a read only status file. The first line has a length of 32 bytes
including the newline and starts with the string
.B bufsize
followed by the prefered write unit (in bytes) and the string
.B buffered
followed by the number of bytes currently queued for output. The
numbers are decimal and right-padded with spaces to fit.
After this fixed header, the contents of the file is driver specific.
.PP
.B Volume
is the control file associated with the audio port.
Each input and output source has an associated stereo volume control,
is the control file associated with the audio port. Each source has
an associated stereo volume control,
ranging from 0 (quiet) to 100 (loud).
In addition, there are controls for the sampling rate of the D/A and A/D converters
In addition, there are controls for the sampling rate,
latency control and for any tone controls.
Reads
return lines of the form
.IP
.I source
.B in left
.I value
.B right
.I value
.B out left
.I value
.B right
.I left
.I right
.PP
or
.IP
.I source
.I value
.PP
possibly abbreviated if the values are shared or non-existent.
For example, if all of the values are shared, the form degenerates to
.RI ` source
.IR value '.
Valid sources depend on the particular audio device,
though all devices have an
.B audio
stereo source, which controls the output volume from the D/A converter
connected to
.BR audio .
stereo source, which controls the output volume from the D/A converter.
Values for
.B speed
set the sampling frequency of the audio device and
.B delay
limits the audio data output buffering to a number of samples.
.PP
Writes accept the same format with same abbreviations.
Writes accept the same format except that for stereo sources
.I left
and
.I right
can be abbreviated to a single
.I value
if both should be set the same.
.SH SOURCE
.B /sys/src/9/port/devaudio.c
.SH SEE ALSO